Improvement in processes of hardening and toughening the surface of cast-iron



TNITED STATEs JOHN s. nomnson, or cnnnnnareun, new roan.

IMPROVEMENT IN PROCESSES 0F HARDENING AND TOUGHENING THE SURFACE OF CAST-IRON MOLD-BOARDS, 8m.

Epecification forming part of Letters Patent No. 145,849, dated March 24, 1874; application filed March 10, 1874.

To all whom it may concern.

Be it known that I, J OHN S. Ronmson, of the town of Oanandaigua, county of Ontario, and State of New York, have invented a new and Improved Method or Process for Hard ening and Toughening the Surfaces of Cast- Iron, so that such surfaces shall partake of the character, strength, and durability of steel, of which the following is a specification:

The nature and object of my'invention is, primarily, to apply the process herein described to the mold-boards of plows; but the principle involved is susceptible of application to the surfaces of cast-iron of any other form or configuration equally as well, and with beneficial results.

In order to enable others skilled in the art to make, use, and employ this my method and process, I will proceed to describe the same.

The initial steps taken are similar to those taken in the production of castings, &c., and are as follows: A nowelboard is placed in a proper position to receive upon it what is denominated a chiller, made of metal. Upon this is placed the mold-board or other pattern. Aroundboth the chiller and pattern is then packed molding-sand, covering the sides of the same up to the edge of the upper surface of such pattern. The molding sand is sloped downward to the nowel or bottom board. \Vhat is denominated pasting-sand is then applied to the exposed surface of the pattern, and the cope applied, which is filled and packed with sand, after which the cope is removed, and the pattern taken off from the chiller. The chiller is then removed, and heated sufficiently to expel all gases or moisture, and allowed to cool down to a moderate degree of temperature, after which it is read justed to its former position in the mold. The cope is again replaced, and the molten iron then poured upon the chiller while the latter is yet warm, and filling the place formerly occupied by the pattern.

The further manipulation of the material constitutes my improved process: The flask is then reversed, the bottom removed, and the chiller taken from the same, leaving the cast mold-board or other casting with its under surface exposed while at a red heat. This casting is then covered with pulverized charcoal, of suflicient fineness to come in contact with substantially its whole exposed surface, causing ignition of the charcoal the whole being then covered with sand, the bottom board replaced, and the flask returned to its first or normal position, and allowed thus to remain until the casting is cold. The casting or moldboard, while in its red state, is not in a fit condition to be removed, but is in such a condition to absorb from the charcoal all the carbon which the latter contains, and in a more perfect manner than by any process known; and by means of this absorption upon and within this exposed surface I produce the result desired and claimed by 1neof hardening, toughenin g, and producing substantially a steel surface upon the cast-iron pattern.

It is considered that, by this process, cheapness and facility of construction are obtained to adegree hitherto unemployed and unknown that too rapid contraction of the chilled side of the casting is prevented; that the opposite surface is more uniformly hardened and toughened, and thoroughly carbonized, and thus is the tendency of the casting to become warped or cracked avoided.

What I claim as my invention, and desire to secure by Letters Patent, is

1. The within-described process for hardening and toughening the surfaces of cast-iron mold-boards for plows.

2. The employment of pulverized charcoal, and the application of the same to heated surfaces of cast-iron when the latter is in such a condition to produce combustion of said charcoal, in the manner and for the purpose herein specified.

JOHN S. ROBINSON.

Witnesses:

B. F. JAMES, F. H. HARRIS. 

